A method for manufacturing a TFT in the prior art includes a step of forming a pattern of source/drain electrode by a patterning process. To be specific, after a photoresist is coated on the TFT provided with a gate electrode, the photoresist is subjected to an exposure treatment so as to form a pattern identical to the pattern of source/drain electrode, and then subjected to etching by means of an etching method including one etching step and one dry etching step so as to form the pattern of source/drain electrode, a pattern of semiconductor layer, a pattern of doped semiconductor layer, and a channel region. The etching method includes: wet etching a source/drain metal layer using a diluted etchant, so as to form the pattern of source/drain electrode and the channel region; and dry etching the pattern of semiconductor layer and the pattern of doped semiconductor layer, so as to form the pattern of semiconductor layer and the pattern of doped semiconductor layer identical to the pattern of source/drain electrode.
However, the etching method including one wet etching step and one dry etching step causes an undercut between the pattern of semiconductor layer and the pattern of doped semiconductor layer.